Strain relief for the terminal connections of electrical devices



' 9 7 1927' w. w. MILLER 646 038 I smmz RELIEF F'OR'THE TERMINALcommcnous OF ELECTRICAL mmcss Filed June 29, 1922 IN VEN TOR.

ATTORNEY Patented Oct. 18, 1927.

UNITED STATES.

A NT OFFICE:

WILLIAM W. MILLER, OF NEW YORK, N. Y., ASSIGNOR TO THE CUTLER-.I-IAMMER00.; OF MILWAUKEE, WISCONSIN, ACORPQRATION OF WISGONSIN.

. STRAIN. RELIEF FOR THE TERMINAL CONNECTIONS or ELECTRICAL DEVICES.

Application med June 29, 1922. Serial No. 571,651.

" for equalization ofthe strains on the terminal connections and whichinsures against short circuiting thereof.

Various other objects and advantages of p the invention will hereinafterappear.

The accompanying drawing illustrates an embodiment of the inventionwhich will now be described, it being understood that the embodimentillustrated is susceptible of modification without departing from thescope of the appended claims.

In the drawing Figure 1 is a longitudinal sectional view 5 of a heaterunit having-strain relieving means embodying the invention associatedtherewith.

Fig. 2 is a sectional view on line 2-2 of Fig. 1; and

Fig. 3 is an end view of the unit shown in Fig. 1.

The of the immersion type and comprises a U- shaped heater element 1said element including an insulated resistance wire enclosed within atubular casing 2 and provided with terminal devices 3 and 4. Casing 2fits within openings in a plug member 5, the same being held within saidopenings by soldered joints 6. Plug member 5 is provided with a threadedportion 7 on the exterior thereof to be screwed into a threaded openingin a receptacle-or other device and the same fits within a cover member9 secured thereto by screws 10. Cover 9 is provided with an insulatinglining 11 and. the end wall thereof is perforated to receive ashouldered insulating bushing 12. Bushing 12 is held within cover member9 by a cap 13 riveted to the end wall of said member and said bushingprojects inwardly beyond the end wall of lining 11. r

The strain relieving means nal wires of the aforedescribed heater unitincludes annular insulating washers 14 and heater unit shown in thedrawing is.

for the termi- 15 I preferably ofiresilient materialqthe formerbeingadapted to abutthe end face of bushing 12 andthe latter beingarranged 7 between the former and terminal devices 3 and 4. The openingin washer 14 is of sufficientdiameter to accommodate .terminal wires-16and for a purpose hereinafter set forth, said wash'er projects outwardlybeyond bushing 12 while the opening in washer 15 is of largerdiameterthanithe opening in washer 14.

In connecting the heater unit to the terminal wires 16, cover 9 isdetached from plug member 5 and the same together -with' washer 14 is"slipped over said wires. The ends of the terminal wires are then passedthrough the opening in'washer 15 and after looping the same'around theouter edge of said washer and returning the same through said openingconnection is made with terminal devices 3 and 4. The loops in theterminal wires are then arranged on opposite sides of the washer 15 andsaid washer is adjusted so that upon replacement of cover 9 washer 14will abut the end of bushing 12, to maintain a slight amount of slack inthat portionof the terminal wires leading to terminal devices 3 and 4. Ar 7 From the foregoing it is apparent that outward strain on theterminal wires 16 clamps the looped portions between washers l4 and 15and prevents slippage of said portions around washer 15. Further itshould be noted that washer 15 is adapted to yield under strains imposedthereon by the looped portionsof terminals 16 and upon inequality in thestrains on the terminal wires the same is adapted to be distorted toequalize such strains. It is apparent that the aforedescribed strainrelieving means is not limited to electrical devices of the characterdescribed and if desired the same can be employed in connection withelectrical devices having three or more terminals.

What I claim as new and desire to secure by Letters Patent is:

1. The combination with an electrical device including a base having.spaced terminal devices thereon, a cover for said terminal devices,terminal wires passing through an opening in said cover and connected tosaid terminal devices and strain relieving means within saidcoverincluding a plurality of washers through which said wires'extend I oneof said washers having said terminal wires looped around the same andanother of said washers being interposed between 'the looped portions ofsaid wires and said cover.

2. The Combination with an electrical de vice including a base havingspaced terminal 7 thereon and being adapted to yield under such strains.

3. The combination with an electrical device including a base havingspaced. terminals thereon, a cover fixed to said base and enclosing saidterminal devices, terminal wires connected to said devices and passingthrough an opening in'said cover, an insulating bushing within theopening in said cover and-strain relieving means for said terminal wiresincluding a plurality of perforated washers through which said wiresextend one of said washers having said termi nal Wires looped around thesame at substantially diametrically opposed points and the other of saidwashers beingarranged between the looped portions of said terminal saidwires extend, said wires being looped around one of saidmembers toprovide a clamping action against the other of said members'in'the eventofa pull. on either or both ofsaid wires.

' 5. 'A strain relieffor conductor terminals comprising a base havingspaced terminal devices thereon, terminal wires connected to saiddevices, a cover having an Opening thereinfor receiving said terminalwires, a pair of insulating members su ported by said wires, means onsaid cover or limiting the outward movement of one of said members, saidwires being passed through and looped around the other of said membersto provide a clamping action between said members upon an outward pullon said w res. V a

In witness whereof, I have hereunto subscribed my name.

WILLIAM MILLER.

